Vehicle drive apparatus

Abstract

A vehicle drive apparatus includes a motor generator, a speed reduction mechanism connected to a rotor shaft of the motor generator, an output shaft connected to the speed reduction mechanism, an intermediate wall separating the motor generator from the speed reduction mechanism, and a bearing that is fixed to the intermediate wall and supports the rotor shaft. The motor generator, intermediate wall, speed reduction mechanism, and output shaft are disposed in this order, and a ring gear of the speed reduction mechanism is fixed. The ring gear is fixed to the intermediate wall via a ring gear flange that is positioned relative and fixed to the intermediate wall by a centering mechanism and a locking mechanism. The centering mechanism is formed by fitting a boss of the ring gear flange and the intermediate wall. The locking mechanism is disposed on an outer peripheral side relative to the centering mechanism.

Description

INCORPORATION BY REFERENCE[0001]The disclosure of Japanese Patent Application No. 2010-081557 filed on Mar. 31, 2010 including the specification, drawings and abstract is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to a vehicle drive apparatus that outputs rotation of a motor generator from an output shaft by reducing a speed of the rotation through a speed reduction mechanism, and more specifically, to a vehicle drive apparatus including a ring gear fixed in a speed reduction mechanism.DESCRIPTION OF THE RELATED ART[0003]A known vehicle including a motor generator as a drive source (for example, a hybrid vehicle and an electric vehicle) includes a speed reduction mechanism that transmits rotation of the motor generator to an output shaft by reducing the speed of the rotation. The speed reduction mechanism includes a sun gear, a carrier, and a ring gear. Of these components, either the carrier or the ring gear needs...

AI Technical Summary

Benefits of technology

The present invention provides a vehicle drive apparatus with a speed reduction mechanism that reduces gear noise. By fixing the ring gear in the speed reduction mechanism, the ring gear can be easily centered, resulting in reliable reduction of gear noise. This improves the overall performance of the vehicle drive apparatus and provides a better user experience for users.

Problems solved by technology

However, when the ring gear is fixed to the case on the outer periphery of the ring gear, this fixing disables alignment through meshing between the ring gear and the pinion gear.

Machining the inner surface of the case is, however, difficult (it is technically possible, but becomes highly expensive).

Specifically, when the ring gear is fixed, if the ring gear is fixed to the case on the outer periphery of the ring gear, achieving good axis accuracy of the ring gear is practically difficult.

The aggravated axis accuracy of the ring gear could result in poor tooth contact between the ring gear and the pinion gear.

The poor tooth contact results in reduced gear durability and aggravated gear noise.

If the axis accuracy of the ring gear is not achieved, however, the gear noise emitted from the case cannot be reduced.

JP-A-2009-168142 does not, however, mention centering of the ring gear, and therefore, it is highly likely that the gear noise emitted from the case will not be reduced with the art disclosed in Japanese Patent Application Publication No.

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